1. Technical Field
The technical field relates to an imaging apparatus such as a digital still camera, and in particular, to an imaging apparatus capable of recording, in a recording medium, RAW data which is created based on image data generated by an imaging device.
2. Related Art
In digital imaging apparatuses using a layer imaging device, such as digital still cameras, any one of a plurality of kinds of color filters is arranged on a front side (on a subject side) of each of pixels constituting the imaging device.
FIGS. 8A to 8E show color arrangement patterns of color filters. R represents a red color filter, G represents a green color filter, and B represents a blue color filter. FIG. 8A shows a color arrangement pattern of color filters so-called “Bayer array” in which G color filters are staggered and R and B color filters are interlaid in positions where G color filters are not present. FIG. 8B shows a color arrangement pattern of color filters in which G color filters are arranged in stripes and R and B color filters are interlaid in columns where G color filters are not present. FIG. 8C shows a color arrangement pattern of color filters in which G color filters are arranged in a honeycomb pattern so as to surround R and B color filters.
While FIGS. 8A to 8C show color arrangement patterns of primary color filters, as shown in FIGS. 8D and 8E, various color arrangement patterns of complementary color filters have also been proposed. In FIGS. 8D and 8E, C presents a cyan color filter, Y represents a yellow color filter, M represents a magenta color filter, and G represents a green color filter. Primary color filters are used as color filters in the description below.
The image data outputted from the imaging device having the color filters arranged on the front side are generally referred to as “RAW data”. The RAW data are image data having a configuration that corresponds to the pixel positions of the pixels constituting the imaging device. Accordingly, in the case of the primary color filters, only pixel data of a color that corresponds to any of the R, G, and B color filters are present in the pixel positions of the pixels.
Thus, at each pixel position, pixel data (pixel value) of a color corresponding to a color filter that is not disposed in the pixel is obtained by interpolating the pixel data (pixel values) of the peripheral pixels. For example, the image data of colors corresponding to red and blue are interpolated from the image data of the peripheral pixels on which R and B color filters are disposed (“R and B color filters-disposed-peripheral pixels”) into the image data of the pixels on which G color filters are disposed (“G color filter-disposed-pixels”). In this manner, image data corresponding to all red, green, and blue colors are obtained at the respective pixel positions of the pixels.
Japanese Patent No. 3862506 discloses a technique of interpolating pixel data of a color corresponding to a color filter that is not disposed on a pixel from the pixel data of the peripheral pixels, as described above.
Recently, with the remarkable growth in capacity of data-recording media for digital imaging apparatuses such as digital still cameras, there is an increasing demand to record not only JPEG data but also RAW data in the recording media. Recording RAW data enables various processes that are not possible with JPEG data to be repeatedly performed by using image processing software loaded on personal computers. The image processing software is generally referred to as “developing software”.
In recording JPEG data, Y/C separation is performed on the image data obtained by interpolating the image data of a color corresponding to color filters that are not disposed in certain pixels from the image data of the peripheral pixels, so as to create Y/C data. Then, various correction processes are performed on the Y/C data, and the resultant data are compressed in JPEG format to create JPEG data.
Meanwhile, in recording RAW data also, the user may want to perform correction on the RAW data before recording it. For example, it is difficult to correct aberration, such as distortion that exists inevitably in imaging optical systems, with image processing software. Thus, it is desired that correction of distortion and the like is performed before recording the data from the imaging device as RAW data. Such correction is performed through partial enlargement/reduction of image data, but the RAW data generally contains pixel data of one color per pixel position. Consequently, in the form of RAW data, it is not possible to perform partial enlargement/reduction of image data for correction of distortion and the like in the conventional art.
Further, in a case where, in performing image processing with developing software, RAW data of a large size are not necessary and only RAW data of a small size suffice, if reduced RAW data can be recorded, it becomes possible to increase the number of RAW data that can be recorded in the recording medium as well as to cut the processing time required for recording the RAW data.